Which viewer am I using?

Since July 1st 2009, there are 2 types of viewers: the 32bit viewer and the new x64 viewer.
The difference is that the old x32 viewer will not work on 64bit operating systems (Vista x64, Windows 7 x64) because it's using old HASP hardware key drivers.

To check which viewer (x32 or x64) you are using, go to the 'About' box via the menu (Help/About). On the bottom of the about box, you can find the build number.
-If there is nothing display below this line, you are using the old 32bit viewer.
-If there is displayed 'Keynr: 32bit version', you are using the old 32bit viewer.
-If there is displayed 'Keynr:' and anything other than above, you are using the new viewer with 64bit drivers.

The new viewer is available since July 1st 2009 and requires different drivers and possible a new hardware key. Read this document to see if you can upgrade easily: Upgrading HASP drivers

To check if a new version of your viewer is avaiable, go to Updating the viewer.

The x32 viewer will be maintained until January 1st 2010. After this, you have to upgrade to the new viewer. See the upgrading-document link in the previous sentence.